The matchinglaw states that the absolute amount of each form of behavior is proportional to the relativeamount of reinforcement associated with it. While the law has been confirmed, at least approximately, in numerous experiments, the procedures used have, for the most part, been similar. The main objective of this research is to test the limits of generality of the law, by examining different drives, different forms of responding, different kinds of contingencies between behavior and consequence, and, to a limited extent, different species. A secondary objective is to investigate the ties between the matching law and the learning process or processes.